The present invention relates to a hospital bed having the capability of weighing a patient located on the bed. More particularly, the present invention relates to an improved scale mounting apparatus for a hospital bed or other piece of equipment.
In certain instances, such as in intensive care or critical care units of a hospital, it is necessary to monitor a patient's weight on a regular basis. Therefore, various scale devices have been designed to accomplish weighing of the patient. In certain scale devices, a patient must be transferred to a separate scale or to a sling scale device for weighing the patient. See, for example, U.S. Pat. No. 4,551,882. In other instances, thin weighing scales are adapted to be placed under the patient. See, for example, U.S. Pat. Nos. 3,217,818 and 3,463,368. Other scales require the entire bed to be located on the scale. See, for example, U.S. Pat. No. 4,281,730.
The present invention relates to an improved scale mounting system for mounting a scale apparatus directly onto the bed to obtain a weight of the patient without moving the patient or the bed. In other words, the scale of the present invention is integrated with the frame system of the bed. Other such integrated scale devices are known. See, for example, U.S. Pat. Nos. 4,953,244; 4,793,428; and 5,269,388. These known scales typically include load cells or linear variable differential transformers for measuring the weight of a patient on the bed.
U.S. Pat. No. 4,953,244 discloses a weigh frame coupled to a patient support surface. The weigh frame is mounted at its four corners by load cells to a bed support frame. The weight detected by the four load cells is summed and processed to provide a weight of the patient. The present invention provides an improved scale mounting apparatus for securing a weigh frame to a support frame with load cells to each corner of the weigh frame.
Typically, the load cells used to measure the weight of the patient are sensitive to side loading. Such side loading can create weight errors. The mounting apparatus of the present invention provides a more stable mounting system which improves the linearity of the output from the load cells.
The mounting apparatus of the present invention is easier to install, provides improved frame stability, increases accuracy and repeatability of the measurements from the load cells, and reduces costs of production and installation.
According to one aspect of the present invention, a scale mounting apparatus is provided for coupling a fixed support frame to a movable weigh frame. The apparatus includes a load cell having a first end rigidly coupled to the support frame and a second, movable end, a mounting bracket coupled to the weigh frame, an elastomeric mounting block, and a fastener for coupling the mounting block and the mounting bracket to the second movable end of the load cell.
In the illustrated embodiment, the mounting block has a cylindrical shape. The mounting block has a hardness of about 70 to about 80 durometer.
The illustrated embodiment also includes a washer located between the fastener and the mounting block. The washer includes an outer flange configured to extend over a lower portion of an outer surface of the mounting block. The illustrated mounting bracket is formed to include a recessed section for surrounding an upper portion of the outer surface of the mounting block.
Also in the illustrated embodiment, the fastener extends through a central aperture formed in each of the washer, the mounting block, the mounting bracket and into the second end of the load cell. The first end of the load cell is coupled to a bottom surface of the support frame, and the second, movable end of the load cell includes a mounting surface aligned generally parallel to the bottom surface of the support frame. The mounting surface includes a threaded aperture aligned with an opening formed in the bottom surface of the support frame. The threaded aperture is configured to receive a threaded end of the fastener to secure the mounting block and the mounting bracket to the load cell. A head of the fastener is located outside the support frame to facilitate installation of the scale mounting apparatus.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.